Used to keep coffee crystals from falling into the coffee pot as it is being brewed.

After one grinds up coffee beans, he may place them in a coffee filter and place it in the coffee machine then fill it with water and turn it on and wait for it to brew. Alternatively, he could pour the methamphetamine mixture and let the filter catch the crystals, scrape them out and sell them, then add the coffee to the filter and have the kickest ass fucking pot of coffee ever brewed.